A transmit diversity mobile device may have multiple antenna elements to each transmit a signal, such that the signals combine at a base station, for example, the signals being typically being sent over the same frequency. The signals sent on the respective antennas may differ by a transmit diversity parameter, e.g., a phase difference or a power ratio. The transmit diversity parameter may be modified to perform beamforming so as to optimize reception quality, e.g., minimize signal loss, at the base station. Such determination of the transmit diversity parameter value may be made by the base station based on prior mobile device diversity signals and communicated expressly to the mobile device, i.e., “closed loop” feedback mode, or may be made by the mobile device based on an analysis of signal quality, e.g., based on power control feedback signals received from the base station, i.e., “open loop” mode.
A mobile device may contemporaneously receive feedback signals from multiple base stations, for example, when the mobile device is within range of a plurality of base stations. This is typically referred to as a soft handoff situation. The mobile device is typically programmed to obey the feedback signals of the serving base station, which is typically the base station sending data to the mobile device. However, in a soft handoff situation, obeying feedback signals from the serving base station may cause the mobile device to interfere with non-serving base stations which may be located nearby.